A response surface methodology (RSM) based optimization method for improving the performance of a LS-band voltage controlled oscillator (VCO) was proposed. A LC-VCO circuit was designed as an optimization target, and the phase noise and power dissipation were improved by employing cascade cross-coupled transistors as load-resistance and an external current mirror bias. Furthermore, the RS model was constructed by fitted data based on circuit simulations, then the best design parameters and the corresponding electric performance could be obtained as the optimal solution. Based on TSMC CMOS 65 nm/1.8 V RF process, the final results showed that all performances of the proposed VCO were improved significantly after optimization. The VCO had a tuning range of 2.377 GHz~2.583 GHz, i.e. 206 MHz, a phase noise of -113.44 dBc/Hz@1 MHZ, and a power consumption lower than 0.66 mW. The FoM value could reach 184.27 dBc/Hz. The proposed LS-band VCO could be applied to the RF transceiver integrated circuits in WiFi, Internet of Things (IoT) and other wireless communications.